Control for a muscle or motor-powered drive

ABSTRACT

A control for a motor drive of a device that is movable, in particular, drivable, by a muscle power drive as well as, in a supporting function, the motor drive, including an apparatus, detecting kinematic parameters of the moving device and generating motor drive control signals, for adjusting a degree of support action for the muscle power drive by means of the motor drive based exclusively on the detected kinematic parameters, wherein the kinematic parameters relate to a movement component which is based on at least one of the periodic fluctuation of the exerted muscle driving power inherent in the muscle power drive and a change of the exerted muscle driving power in reaction to a certain change of the motor driving power or the motor driving speed.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a control for a motor drive of a device that ismovable, in particular, drivable, by muscle power as well as, in asupporting function, by the motor drive, comprising an apparatus,detecting kinematic parameters of the moving device and generating motordrive control signals, for adjusting a degree of support action for themuscle power drive by means of the motor drive based exclusively on thedetected kinematic parameters.

2. Description of the Related Art

Drives which are based on muscle power as well as motor power are knownfrom drivable devices, such as bicycles or golf carts. In thisconnection, the motor drive has a supporting function in that itprovides, for example, a portion of the total required driving powerwhich surpasses a basic load to be provided by muscle power. The totalrequired driving power results from the behavior of the user of thedrivable device who, for example, wants to accelerate or/and maintain acertain speed under the different drive path conditions that arecharacterized by different inclines or the ground conditions.

A control, known from WO 05/03096, for a drive based on muscle power aswell as motor power for a drivable device is based on a continuousmeasurement of the applied muscle driving power and a control of themeasured driving power to a predetermined value. In the context of thiscontrol, the drivable device is adjusted by the motor driving power suchthat the user feels a constant drive resistance corresponding to thisvalue and, thus, to the basic load.

U.S. Pat. No. 5,664,636 describes a control for an electric auxiliarydrive of a pedal-driven vehicle in which the aforementioned apparatusfor generating motor drive control signals detects, in addition to thespeed of the vehicle, continuously the pedal power. The support actionby means of the auxiliary drive is adjusted by means of a storedreference table in which desired driving powers correlated to thedriving speed and the pedal power are stored.

Controls of the aforementioned kind in which the generation of motordrive control signals is carried out exclusively by means of thedetected kinematic parameters are disclosed in EP 0 734 945 A1 as wellas WO 96/32314. The control known from EP 0 734 945 A1 for a motor driveof a bicycle comprises an acceleration sensor which can be embodied by aspeed sensor and a differential device. Based on the determinedacceleration values, motor drive control signals are generated whichprovide for a change of the drive support action by the motor drive sothat the pedal driving power required during the time period ofacceleration of the bicycle is accordingly reduced. For changing thedrive support action, the switching ratio of the drive motor operatedwith pulse width modulation is varied. In the control known from WO96/32314 the speed of the vehicle driven by muscle and motor drivingpower is continuously determined and the motor driving power is adjustedaccording to a stored functional relation between the motor drivingpower and the speed of the vehicle.

SUMMARY OF THE INVENTION

With the present invention, a new control of the aforementioned kind isprovided in which the aforementioned kinematic parameters relate to amovement component which is based on the periodic fluctuation of theexerted muscle driving power inherent in the muscle power drive or/and achange of the exerted muscle driving power in reaction to a certainchange of the motor driving power or the motor driving speed.

Preferably, the aforementioned apparatus is designed for generatingmotor driving power control signals according to a desired support orrelief of the muscle power drive by means of the motor power drive,wherein the support action can be realized according to a desiredproportion of motor power relative to the total driving power oraccording to an optionally adjustable constant basic load to be providedby the muscle power drive.

In a preferred embodiment of the invention the aforementioned apparatusis designed for determining and evaluating time functions of kinematicparameters and comprises especially an analytical device comprising adifferential device for evaluating the time functions. According to thisembodiment, a device for detecting travel-time-functions orspeed-time-functions could be provided wherein optionallyacceleration-time-functions and time functions of higher derivatives canbe formed with the aid of the differential device.

The muscle power drive may be, for example, the pedal drive of a bicyclein which a circular drive motion results by actuation of the pedal crankdevice. According to the conditions of the muscle power generation andtransmission in such a drive, the driving power that can be transmittedonto the pedals fluctuates for such a drive such that the driving powerhas a minimum in the vertical position of the pedal crank and has amaximum in the horizontal position of the pedal crank. According to thisfluctuating driving power, the acceleration or/and speed profile of thebicycle powered by a muscle power drive has a periodic component. Theamplitudes of the periodic components depend on the average pedalingforce.

Such a periodic component also results for a muscle power drive in whicha running movement is realized by exerting a pulling or pushing forcetransmitted, for example, onto a drivable device. According to the powergenerating and transmission conditions changing with the runningmovement, a periodic increase and decrease of the pulling or pushingforce results, wherein these fluctuations are the greater, because ofthe increasingly stronger coupling action via the muscle tension, thegreater the transmitted average pulling or pushing force.

For generating control signals, the aforementioned apparatus canevaluate the amplitudes of the periodic components of the speed or/andacceleration profiles wherein an average speed or/and accelerationoverlaying the periodic component can be taking into account. In thisevaluation, the amplitudes are preferably compared to a predeterminedstored amplitude wherein the stored amplitude can be selected accordingto a basic load to be supplied by the muscle power drive.

Inasmuch as the signal generation is carried out with the goal that acertain basic load is to be provided by muscle power, the control signalgeneration by the aforementioned apparatus can be performed bycontrolling the amplitude of the periodic component of the detectedspeed profile to the predetermined amplitude.

In a further embodiment of the invention, the determination of kinematicparameters is based on a predetermined model of the drive behavior of auser of the device who supplies the muscle power. Such a behavior modelcan be, for example, typical drive movements for certain drivesituations, for example, the initial muscle-powered movement whenstarting to drive the drivable device. In reaction to such an initialdriving movement, which can be determined by comparison withcorrespondingly stored movement courses, control signals for a suitableactivation of the motor drive can be generated.

The behavior model is a reaction model which results from certainchanges of the drive action by the motor drive, wherein thepredetermined changes of the drive, for example, may reside in the slowincrease or decrease of the motor driving power or driving speed andwherein the aforementioned apparatus is designed for switching fromincrease to decrease of the motor driving power or speed when themovement of the driven device decelerates and for switching fromdecrease to increase when the movement of the driven device accelerates.Such a control is based on the idea that, when, for example, the motordriving power increases, the user is reducing the muscle powercorrespondingly for the time period for which he desires a support bythe motor drive. When the user no longer reduces the muscle drivingpower to the degree in which the motor driving power increases, anacceleration is caused, and form this it can be deduced that the userfinds this motor driving power, that has increased up to the point ofacceleration, desirable. In the reverse situation, when the motordriving power decreases slowly, a negative acceleration of the drivabledevice results when the user no longer increases the muscle drivingpower accordingly, and, based on this, the aforementioned apparatus candetermining that the motor driving power reached at the point where thenegative acceleration occurs is the desired motor driving power. In thisway, the driving support action desired by the user of the drivabledevice will be automatically adjusted.

BRIEF DESCRIPTION OF THE DRAWING

The invention will now be explained and described in more detail withthe aid of embodiments and the attached drawings which relate to theseembodiments. It is shown in:

FIG. 1 a schematic representation of the control according to theinvention;

FIG. 2 speed and acceleration profiles detectable by the control of FIG.1 and evaluated for generating motor drive control signals;

FIG. 3 further speed and acceleration profiles that can be evaluated bythe control of FIG. 1 according to the invention;

FIG. 4 a representation explaining the formation of the profiles ofFIGS. 2 and 3; and

FIG. 5 a diagram for explaining one embodiment of the control accordingto the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In FIG. 1, the reference numeral 1 refers to a drive motor of a drivabledevice, not shown, for example, a bicycle or a golf cart. The motor 1 issupplied by a power control 2 comprising a battery and receiving controlsignals generated by the device 3. The control signal generating device3 is connected to the speed measuring device 4.

The speed measuring device 4 comprises in the shown embodiment a pulsegenerator detecting positional changes of the drivable device andgenerating pulses in a number proportional to the rotational angle ofthe shaft of the drive motor 1. The speed measuring device 4 comprisesmoreover a time measuring device and a computing device in order tocompute, based on the measured pulse numbers and times, the rotationalspeed of the drive shaft which is proportional to the translatory speedof the aforementioned drivable device. The time measuring device and thecomputing device as well as the control signal generating device 3 areimplemented by a computer wherein the control signal generating devicecan also detect and evaluate directly positional changes of the drivabledevice via the pulse generator.

The drive motor 1 is a separately excited multi-pole three phase currentsynchronous motor which is star-connected. This motor may itself serveas a pulse generator of the speed measuring device 4, wherein, forexample, corresponding voltage pulses, formed by induction on theexcitation poles, can be tapped at the star point. Reference is nowbeing had to FIG. 2, wherein speed profiles of a bicycle or a devicewhich is pushed or pulled by a person, for example, a golf cart, areshown in partial Figure a. In the shown example, the speed profiles havea constant speed component X_(k) which is overlaid by a periodiccomponent. This means that the drivable device is moving with a constantaverage speed X_(k).

FIG. 4 shows how speed profiles, as those shown in FIG. 2a, result from,for example, a bicycle driven by a muscle power drive with constantaverage speed.

FIG. 4a shows the bicycle pedal cranks 9 and 10 each having a pedal 11and 12 and being connected to the chain drive wheel 8. An arrow is shownat 13 illustrating a tangential driving power exerted in the verticalposition of the pedal cranks. The arrow 14 indicates the tangentialdriving power in the horizontal position of the pedal cranks. Asindicated by the different sizes of the arrows 13 and 14, in thevertical pedal crank position a substantially reduced tangential drivingpower P_(T) is exerted as compared to the horizontal rotational positionof the pedal cranks 9 and 10, wherein the tangential driving power P_(T)has approximately the periodic course illustrated in FIG. 4b as afunction of the rotational angle α of the crank drive wheel 8.

According to this periodic course of the tangential driving power P_(T),the acceleration profiles 5 a to 7 a illustrated in FIG. 2b result forthe bicycle driven by means of the pedal cranks 9 and 10. By integrationover time the speed profiles 5 through 7 of FIG. 2a result.

Because of the proportional relation between the driving power and theacceleration, the amplitudes of the periodic profile components are thegreater the greater the average tangential driving power according toFIG. 4b is. When there is no muscle power load, i.e., when the bicyclistdoes not pedal or pedals along without load, the periodic component ofthe speed profile will disappear.

When driving a drivable device by a running movement and exertion of apulling or pushing force, profiles similar to the profiles of FIG. 2result because of the varying force transmission conditions of the stepmovement. The amplitudes of these profiles also increase with increasingaverage muscle driving load, and the periodic profile componentdisappears when, for example, the pulling rod of a golf cart is onlyheld without transmission of a pulling force or a (decelerating) pushingforce.

The control signal generating device 3 illustrated in FIG. 1 comprisesin the shown embodiment a differential device by which, based on thespeed profiles shown in FIG. 2a, the acceleration profiles shown in FIG.2b can be computed.

The profiles shown in FIG. 2 may result, for example, for a movementovercoming a constant incline or/and a movement in which the drivingpower and a frictional resistance, for example, air resistance, arebalanced.

Reference is now being had to FIG. 3 showing speed and accelerationprofiles for a movement that (on average) is uniformly accelerated ordecelerated.

Also, in the case of such an accelerated movement with constant basicacceleration X_(K) speed profiles 15, 16 and acceleration profiles 15 a,16 a result, each having a periodic component that is overlaid on auniformly increasing average speed or the constant acceleration X_(K).

Speed profiles are indicated in FIG. 3a at 17 and 18 which result for auniformly decelerated movement. Such a movement could be generated by abraking running movement of a person resulting in braking a drivabledevice that has been previously pulled by the person. The accelerationprofiles corresponding to the speed profiles 17 and 18 are indicated by17 a and 18 a whose periodic component is overlaid onto a constantnegative acceleration −X_(K).

In the following the function of the control, explained with the aid ofFIGS. 1 through 4, is described.

During the movement of a drivable device comprising the control devicesof FIG. 1, the device 4 for detecting speeds provides constantlydetected speed values according to the profiles of FIGS. 2a or/and 3 ato the signal generating device 3.

In the shown embodiment the signal generating device 3 evaluates theseprofiles by comparing the amplitudes of the periodic component of thespeed profiles or/and acceleration profiles determined bydifferentiating with a stored amplitude value which corresponds to thebasic load of the drive action of the drivable device to be supplied bymuscle power.

The signal generating device 3 generates then control signals such thatthe amplitude of the periodic components of the sensed speed oracceleration profiles is adjusted to the stored amplitude. This meansthat the motor driving power is increased or decreased resulting inrelief of the supplied muscle driving power such that the exerted muscledriving power corresponds to a speed profile whose amplitude isidentical to the stored amplitude value. In the context of thisadjustment it would also be possible to employ average values X_(K),−X_(K) for the evaluation in order to, for example, determine whether amovement that, on average, is accelerated or decelerated is present.Accordingly, the motor exerts from the start a braking force for anegative acceleration.

In contrast to a control adjustment of the amplitude, i.e., ofindividual values of the profile, it would also be possible to provide acontrol based on further profile values or a control based on storedtotal speed and/or acceleration profiles which correspond to apredetermined basic load to be supplied by the muscle drive action.

Instead of a control to predetermined amplitudes or profiles it is alsopossible to provide a motor control such that a detected periodiccomponent, which indicates the presence of a muscle driving power, ismade to disappear. This means that in this case the motor takes over thecomplete drive output after initial or intermediate muscle power drive.

A third possibility is to control the motor such that a measuredamplitude is reduced by a certain percentage so that it is ensured thatthe motor in any drive situation provides a predetermined, optionallyadjustable, percentage of the total required drive output. In thiscontext, the control could be provided with a device which detects thecurrent motor driving power based on the kinematic evaluation of themovement of the driven device or of the motor drive itself and based ona detection of all voltages supplied to the motor drive and/or currentsflowing therethrough.

Reference is now being had to FIG. 5 wherein the reference numeral 30indicates a time function of the motor driving power P_(m) in partialFigure a. In one operational mode of the control it is proposed that thedriving power P_(m) increases slowly as previously in the portion 31 ofthe aforementioned time function.

When a behavior model is used, according to which a user of the drivabledevice reduces the muscle driving power in the same amount as the motordriving power increases, as long as he desires a stronger support by themotor drive, the speed {dot over (x)} remains constant according to theportion 32 of the speed-time-function 33 illustrated in partial FIG. 5b.

When the user reduces the driving power no longer in the amount of theincrease of the motor driving power, an acceleration of the movementresults at the location 34. The registration of this acceleration in theaforementioned operational mode causes the driving power P_(m) of thedrive motor to now be reduced slowly. However, since the user desires amotor driving power, that is present at the point of acceleration, as adriving support, upon decrease of the motor driving power he will notincrease the muscle driving power for very long in accordance with thedecrease so that at 35 a negative acceleration results which is thecause of a further increase of the motor driving power. Accordingly, onaverage a constant amount of provided muscle driving power is maintainedin the phase 36 of the driving power-time-function. In a subsequentphase 40, the user increases according to the decrease of the drivingpower P_(m) his driving power until the phase 38 of the drivingpower-time-function begins. At this point, this increase no longeroccurs so that at 37 a negative acceleration results. In the phase 38,as in the phase 36, the muscle driving power remains again approximatelyconstant in that the user will counteract sequentially occurring changesof the increase direction of the motor driving power only for shortperiods of time by corresponding changes of the muscle driving power. Inthe described manner the motor drive is adjusted automatically to thebasic load of the muscle power drive desired by the user and varyingover the course of time.

What is claimed is:
 1. Control for a motor drive of a device that ismoved by a muscle power drive as well as, in a supporting function, themotor drive, comprising an apparatus, detecting kinematic parameters ofthe moving device and generating motor drive control signals, foradjusting a degree of support action for the muscle power drive by meansof the motor drive based exclusively on the detected kinematicparameters, wherein the kinematic parameters relate to a component ofthe movement of the entire device which is based on at least one of theperiodic fluctuation of the exerted muscle driving power inherent in themuscle power drive and a change of the exerted muscle driving power inreaction to a certain change of the motor driving power or the motordriving speed.
 2. Control according to claim 1, wherein theaforementioned apparatus (3, 4) is provided for determining timefunctions (5-7; 15-18) of the kinematic parameters.
 3. Control accordingto claim 2, wherein that the aforementioned apparatus (3, 4) comprisesan analysis device for evaluating the time functions.
 4. Controlaccording to claim 3, wherein the analysis device comprises adifferential device.
 5. Control according to claim 1, wherein theaforementioned apparatus is provided for determining periodic timefunctions of at least one of the speed and acceleration.
 6. Controlaccording to claim 5, wherein the aforementioned apparatus (3, 4) isprovided for determining the amplitude of the periodic time functions.7. Control according to claim 5, wherein the aforementioned apparatus isprovided for comparing the determined time function with a predeterminedtarget function, for controlling the determined time function withrespect to the target function by a corresponding change of the motordriving power.
 8. Control according to claim 5, wherein theaforementioned apparatus is moreover provided for determining at leastone of the average speed (19, 20) and acceleration over the periodictime function.
 9. Control according to claim 1, wherein as a directedchange of the motor driving power or speed, a slow increase or a slowdecrease of the motor driving power or speed is provided and theaforementioned apparatus is provided for switching from increase todecrease upon detecting a deceleration and from decrease to increaseupon detecting an acceleration of the device.
 10. Control according toclaim 1, wherein a multi-pole drive motor is provided as a rotationalangle pulse generator for a speed measuring device.
 11. Controlaccording to claim 5, wherein the aforementioned apparatus is providedfor comparing the determined amplitude with a target amplitude, and forcontrolling the determined amplitude with respect to the targetamplitude by a corresponding change of the motor driving power.